Free form identifies a type of seating that includes a casing in the shape of an upholstered chair with no frame. The casing may be made of flexible non-air permeable material such as genuine or artificial leather, plastic, fabric with a coated backing or the like that is partially filled with a filler material such as pieces of expanded polystyrene of various sizes and shapes that can move in the casing under the pressure created by the weight of a seated person.
Under the weight of the seated person the filler is rearranged in the casing by flowing to areas under lower pressure. Therefore, the shape of the casing changes to conform to the shape of the person's body. This customizes the seat to that person's particular body size and shape thereby increasing its comfort.
Free form furniture is advantageous compared to the traditional upholstered furniture since it is relatively simple to make, has low production cost, low weight and high comfort.
In Australian Patent No. 62106/80, an upholstered chair is disclosed that has a casing comprised of flexible, non-stretchable material that is partly filled by flowable particles of styropor. The upper part of the chair forms its seat and continues to form its back and arms. The sides of chair comprise bands of material having different widths which are sewn to the upper and lower parts of the casing.
Flexible non-stretching panels which may be made from non-stretchable sheet-type material are provided to limit the change in the chair's shape when a person sits in it. One panel is generally vertical with one of its edges sewn into the inside surface of the lower part of the casing. Its other edge sewn into the internal part of upper part of the casing where the seat contacts the back. This panel prevents the back part of the seat from rising. This results in the styropor beads flowing under the influence of the weight of the body of the person sitting on the chair.
The second panel is generally horizontal with its edges sewn to the opposite parts of the interior of the sides of the casing. This panel prevents the sides of the casing from stretching under the force of the flowing styropor beads when the seat is loaded, i.e., it limits the enlargement of the cross-section of the seat.
However, after a person leaves the chair it does not return to its original form. This is because the beads that were under pressure from the weight of the sitting person do not return to their former locations in the casing when the person leaves the chair.
Therefore, when the chair is used again, it is necessary to "bulk-up" the chair to its original form by returning the beads to the zones emptied previously. This can be done by hand, or by sitting in it and moving the body to re-spread the beads.
This deficiency is partly overcome by the item described in Russian Patent No. 2,093,057 which has means which enable the beads to return to their original locations after use. This item employs flexible elastic panels that not only define and limit the change in shape of the item, but also help the item to return to its original shape after use.
Moreover, when the elastic panels stretch under a load they create additional volume inside the casing where the beads flow. This occurs because when the casing is loaded by the weight of a person, the elastic panels are deformed. However, when the load is removed the elastic panels return to their original length and the parts of the casing to which they are connected urge the beads to return to the zones which they left under the influence of the load (weight of the sitting person).
However, the Australian and Russian patents are similar since they both disclose a furniture item having a casing made from elastic flexible material with at least one panel inside the casing that is connected at its edges to the upper and lower parts of the casing, and at least one flexible panel which is connected between the sides of the casing.
Moreover, in one instance the flexible panel is fixed to the side of the casing on the perimeter of its cross-section. In another instance flexible panels are fixed the sides of the casing and extend crosswise to the opposite internal surfaces of the side of the casing.
At least one non-stretchable element may be connected to the flexible elastic panel to limit its range of extension and thus limit the change of shape of the item.
None-the-less, even with these features, after repeated uses the beads are crushed to a reduced size and as a result, the total volume of filler in the item is reduced. As less and less of the casing is filled, its shape changes and it becomes less comfortable and less attractive to view.
The change in form is more pronounced at the bottom of the item since the beads in the bottom contact the hard surface of the floor through the material of the bottom part of the furniture item.
Therefore, it is necessary to periodically add additional beads to enable the item to return to its original form. This increases the cost of maintaining the item. For example, if a casing has an internal volume of 100 liters and is 90% filled by beads, and after continuous using (many loadings of the seat) the volume of the beads has dropped by 20%, and as a result the form of the item has changed, 18 liters of beads must be added to compensate for this drop in volume and change of shape. It is obvious that during the life of the item it will be necessary to add the beads several times. This uncomfortable for the person seated. Further, this will increase the weight of the item making it more difficult to move. Still further, maintenance expense may come close to the cost of thee item.
It would be advantageous to provide a filler material that flows smoothly so that the seat would to customize itself to a person's particular body size and shape thereby increasing its comfort.
Further, it would be advantageous if the reduction in volume of the filler material could be compensated for simply and easily without having to open the casing to add filler material.